1. Field of the Invention
The invention is in the field of data communications using optical links to convey wavelength multiplexed signals. It is more particularly concerned with a network architecture particularly suitable for limited geographical areas, such as local area networks. The invention also concerns a switching matrix that can be used in a controller suitable for a network of this kind.
An object of the invention is to design a network capable of supporting uniform or sporadic traffic and bit rates up to a few Gigabits per second and that does not require a complex call set-up protocol.
2. Description of the Prior Art
A network comprises a plurality of stations able to send and to receive messages to and from other stations of the network. Data is exchanged by means of a communication link to which communication nodes associated with the stations are connected. In the case of optical links using optical fibers, for example, their wide bandwidth is exploited to use wavelength multiplexing. Each station or node of the network can be assigned a particular wavelength to convey messages addressed to that node, for example. Each node connected to the optical link sends a message to a destination node by modulating an optical wave having a wavelength associated with the destination node. Each node can receive a message by detecting its associated wavelength.
This solution has various drawbacks, however. Firstly, each node must be able to send each of the wavelengths of the other nodes of the network. It is also necessary to solve problems of collision, i.e. situations in which there is a risk of more than one node sending messages to the same destination. One way to solve this problem is to provide an additional wavelength carrying a synchronization signal and an indication of the occupancy of each wavelength, for example. Each node must then use an access protocol that allows for the occupancy of the destination wavelength. This makes protocol management more complex and limits the throughput of the network.
An object of the invention is to solve the problems raised by the above solution.